Specifically, though not exclusively, the invention is usefully applied in multi-coloured decoration lines for tiles. As is known, decorations requiring several different colours on a same tile are passed under a number of decorator heads corresponding to the number of colours.
Obviously good multi-coloured decorating must involve, as a prerequisite, perfect centring of the various single-colour patterns deposited during the various passages under the heads.
The prior art teaches rotary decorating machines comprising a single mobile rest plane for the tiles, from which the tiles are translated in a predetermined direction, above which plane a plurality of heads are located, arranged one after another. Each of these heads is constituted by a decorating cylinder which has etched upon it the pattern to be reproduced, and which is commanded to rotate about its own axis, parallel to the mobile rest plane and perpendicular to the direction of its movement, so that it rotates without dragging on the tiles. In the most up-to-date machines perfect centring of the etching on the tile, conveyed by the mobile rest plane, is regulated automatically by acting on the individual cylinder, which is commanded to assume the correct angular position in accordance with a tile reaching a predetermined position as it arrives along the mobile rest plane. This is possible thanks to a sophisticated electronic rotation control and an angular position of the cylinder with respect to a reference position.
These realisations, though perfectly functional and able to provide high-performance results, can however be considered too sophisticated for certain types of applications, and, consequently, unsuitable because in the final analysis they are indeed xe2x80x9ctoo perfectxe2x80x9d for the desired results in certain applications.
The main aim of the present invention is to provide a response to the above-cited need for greater simplicity.
An advantage of the invention is that it is constituted by a practically entirely mechanic device.
A further advantage of the invention is that it can be used in any type of rotary decorating machine, including all machines using a drum silk screen method. A further advantage is that the invention is simple and precise and can be rapidly adjusted to ready it for various glazing jobs.